The invention relates to a method of manufacturing a thin-film magnetic head comprising a magnetoresistive element and at least one flux guide, which method starts from a support.
Methods of manufacturing thin-film magnetic heads are known, inter alia from EP-A 0 516 022 (herewith incorporated by reference). The magnetic heads obtained by the methods described in EP-A 0 516 022 are integrated magnetic heads having a contact face and comprising an inductive part and a magnetoresistive part.
In accordance with a first method known from EP-A 0 516 022, a first structured insulation layer of SiO.sub.2 is formed on a magnetic substrate of a ferrite by means of a lithographic method, which layer is subsequently provided with a layer of Au for forming a write coil. Subsequently, a second structured insulation layer is provided on which a core layer of an amorphous material based on Co is deposited. This core layer is in contact with the magnetic substrate via apertures in the insulation layers. The parts of the second insulation layer not coated by the core layer are filled up by means of a filling layer of Al.sub.2 O.sub.3. After the filling layer has been formed, the core layer and the filling layer are planed by means of lapping. A third structured insulation layer of SiO.sub.2 is deposited on the surface thus obtained on which subsequently a bias winding of Au is formed. A fourth structured insulation layer of SiO.sub.2 is provided on this winding. Subsequently, a magnetoresistive element of permalloy is formed on this insulation layer. Then a fifth structured insulation layer of SiO.sub. 2 is provided and subsequently a yoke of an amorphous material which is based on Co and is in contact with the core layer via apertures in the three last-mentioned insulation layers.
In accordance with a second method known from EP-A 0 516 022, two flux guides of a Co-based amorphous material are provided on a non-magnetic substrate, while an aperture between the two flux guides is filled with a first insulation layer of SiO.sub.2. The surface formed by the flux guides and the first insulation layer is provided with a second structured insulation layer on which subsequently a magnetoresistive (MR) element is formed. The MR element is then coated with a third structured insulation layer on which subsequently a bias winding is formed. A fourth structured insulation layer is provided for the purpose of coating the bias winding. Subsequently a magnetic core layer of a Co-based material is formed which is in contact with one of the flux guides via apertures in the three last-mentioned insulation layers. The areas not coated by the first core layer are filled up with a filling layer of Al.sub.2 O.sub.3, whereafter a surface on which an inductive head part is formed is obtained by lapping.
In the methods known from EP-A 0 516 022, the MR element is formed on an insulation layer which is provided on a lapping-processed surface. However, it has been found that such a surface extending on two or more adjacent layers of different material has unevennesses. Moreover, damage particularly in the form of scratches in and disturbances of material under the surface obtained are caused by lapping. Such a surface is inadmissible, inefficient for information transfer and may increase the risk of instabilities in the MR element provided on said surface.
The magnetic heads obtained by the methods known from EP-A 0 516 022 have the further drawback that due to the presence of irregularities on the surface engaging the MR element, a relatively thick insulation layer is required between the MR element and the electrically conducting flux guides so as to ensure a reliable electrical insulation between the MR element and the flux guides. However, such insulation layers have a further negative influence on the efficiency of the magnetic heads. For various reasons, damage in and material disturbance under a surface above which the MR element is present are thus undesirable.